If you can't untick it in MSCONFIG>Startup, try:
- the same after booting in Safe Mode
- deleting that particular line in regedit (Start>Run>regedit) and search for it.
Could anyone advise on this file (I am on windows xp)
HKLM\..\Run: [C:\WINDOWS\system32\kdoio.exe] C:\WINDOWS\system32\kdoio.exe
It showed up on a scan was listed as high risk and was quarantined.
Further checks found it in start up and all attempts to untick it failed. It was also found in Hijack this and all attempts to delete it from hijack have failed.